Try reinstalling iMovie from your System Restore disks (I know you don't have an iLife disk ;)). I still haven't figured out your NSQuickDrawView error but it is probably not causing the crashing.
It probably said it was not supported because it sound like the drive is in the normal PC format, not the Mac HFS+. Your Mac was probably reading or writing to it before it got disconnected. You might not be able to recover if your filesystem is messed up (it sounds like it is).
The missing 50GB could be because of the HFS+ formating of the drive. The 300GB size is when the drive is unformatted. So you only have 100GB free and 150GB used.
Yes, I installed it. You can download it here.
I think it has the full file path because I'm inputing files and folders to where there should be text. Is there any way to make a file name a text file?
Did you not use iMovie HD to do the clips? iMovie is part of iLife. If you bought a Mac recently that came with Leopard installed you have iLife '09.
What program are you using to open the HD videos?